It was Maggie's favorite after-school activity: piano lessons with Mrs. Barton. But one day, Maggie noticed that Mrs. Barton's right hand was shaking, even while she rested it in her lap.

Over time, she noticed other things, too — like the fact that Mrs. Barton wasn't very steady when she walked and that she didn't laugh as much as she used to. It turned out that all the things Maggie noticed were symptoms of something called Parkinson's disease.

What Is Parkinson's Disease?

Parkinson's disease is a disorder of the central nervous system, which includes the brain and spinal cord, and controls everything you do, including moving. A person with Parkinson's disease gradually loses the ability to totally control body movements.

Mostly, it's adults who get this disease.

What Are the Symptoms of Parkinson's Disease?

The symptoms of Parkinson's disease include tremors or trembling (shaking hands are often the most telltale signs of it); difficulty maintaining balance and coordination; trouble standing or walking; stiffness; and general slowness.

Over time, a person with Parkinson's may have trouble smiling, talking, or swallowing. Their faces may appear flat and without expression, but people with Parkinson's continue to have feelings — even though their faces don't always show it. Sometimes people with the disease can have trouble with thinking and remembering too.

Because of problems with balance, some people with Parkinson's fall down a lot, which can result in broken bones. Some people with Parkinson's may also feel sad or depressed and lose interest in the things they used to do.

The symptoms of Parkinson's disease appear gradually and get worse over time. But because Parkinson's disease usually develops slowly, most people who have it can live a long and relatively healthy life.

What Causes Parkinson's Disease?

In the very deep parts of the brain, there is a collection of nerve cells that help control movement, known as the basal ganglia (say: BAY-sul GAN-glee-ah). In a person with Parkinson's disease, these nerve cells are damaged and do not work as well as they should.

These nerve cells make and use a brain chemical called dopamine (say: DOH-puh-meen) to send messages to other parts of the brain to coordinate body movements. When someone has Parkinson's disease, dopamine levels are low. So, the body doesn't get the right messages it needs to move normally.

Experts agree that low dopamine levels in the brain cause the symptoms of Parkinson's disease, but no one really knows why the nerve cells that produce dopamine get damaged and die.

Who Gets Parkinson's Disease?

About 1 million people in the United States have Parkinson's disease, and both men and women can get it. Symptoms usually appear when someone is older than 50 and it becomes more common as people get older.

Many people wonder if you're more likely to get Parkinson's disease if you have a relative who has it. Although the role that heredity plays isn't completely understood, we do know that if a close relative like a parent, brother, or sister has Parkinson's, there is a greater chance of developing the disease. But Parkinson's disease is not contagious. You can't get it by simply being around someone who has it.

How Is Parkinson's Disease Diagnosed?

Someone with the symptoms of Parkinson's disease may be sent to see a neurologist, a doctor who specializes in the brain, nerves, and muscles. The neurologist may do some tests, including a brain scan and blood tests. These tests will not make the diagnosis of Parkinson's disease, but the doctor will want to make sure that there is no other problem causing the symptoms. To diagnose Parkinson's disease, the doctor relies on a person's medical history, symptoms, and a physical exam.

How Is Parkinson's Disease Treated?

If a doctor thinks a person has Parkinson's disease, there's reason for hope. Medicine can be used to eliminate or improve the symptoms, like the body tremors. And some experts think that a cure may be found soon.

For now, a medicine called levodopa is often given to people who have Parkinson's disease. Called "L-dopa," this medicine increases the amount of dopamine in the body and has been shown to improve a person's ability to walk and move around. Other drugs also help decrease and manage the symptoms by affecting dopamine levels. In some cases, surgery may be needed to treat it. The person would get anesthesia, a special kind of medicine to prevent pain during the operation.

Living With Parkinson's Disease

As Parkinson's develops, a person who has it may slow down and won't be able to move or talk quickly. Sometimes, speech therapy and occupational therapy are needed. This may sound silly, but someone who has Parkinson's disease may need to learn how to fall down safely.

If getting dressed is hard for a person with Parkinson's, clothing with Velcro and elastic can be easier to use than buttons and zippers. The person also might need to have railings installed around the house to prevent falls.

If you know someone who has Parkinson's disease, you can help by being a good friend.